EDITORIALS Does Marijuana or Crack Cocaine Cause Cancer?

Epidemiologic studies (1) have indicated a strong association between tobacco smoking and various human cancers, especially lung cancer. Nearly one third of human cancers are estimated to be related to tobacco use. Direct molecular evidence has been provided in a study (2) demonstrating that carcinogens in to-bacco smoke cause a specific type of genetic damage required for cancer development. Fortunately, national anti-cigarette-smoking efforts are expected to reduce the number of teenaged smokers in the next decade and to decrease rates of tobacco-related cancer mortality. However, the number of marijuana smokers is increasing. A national survey by the Department of Health and Human Services (3) indicated that 1.9 % of U.S. high school students smoked marijuana daily in 1992 but that this frequency had increased to 4.6 % in 1995. An independent na-tional survey by the Partnership for a Drug-Free America (4) ha